US3163971A

US3163971A - Method of sterile packing of sterile goods

Info

Publication number: US3163971A
Application number: US158170A
Authority: US
Inventors: Loiiger Willi; Regez Walter
Original assignee: Alpura AG
Current assignee: Alpura AG
Priority date: 1960-12-16
Filing date: 1961-12-08
Publication date: 1965-01-05
Anticipated expiration: 1982-01-05

Description

Jan. 5, 1965 w. LOLIGER ETAL 3,153,971

' METHOD OF STERILE PACKING OF STERILE GOODS Filed Dec. 8, 1961 K a .lm errzars MILL! LOL IGE/E.

ML. r52 PEGEZ.

United States Patent 3,163,971 METHQD 0F STERLLE PACKlNG 9F STERKLE GO0D Willi Liiiiger, Konolfingen, and Walter Regez, hiuri, near Bern, Switzerland, assignors to Aipura AG, Bern, witzerland, a corporation of Switzerland Filed Dec. 3, 1961, Ser. No. 158,170

Ciairns priority, application Switzerland Dec. 16, 1960 8 Clair-i s. ((11. S328) The invention relates to a method of sterile packing of sterile goods wherein a flexible packing material of paper or plastic or the like is sterilized by heating of that side of the material which subsequently contacts the goods to be packaged. The invention relates more particularly to a method wherein a tube of flexible material is formed continuously in a packing and filling machine, Whereafter the tube is partly filled with the substance to be packed and formed into closed filled receptacles by compression transversely of its length, the inside of the formed tube being heated at a location between the introduced substance and the opening of the tube at the location where formation of the tube begins.

Temperatures of 200 C. or more are usually necessary to destroy harmful germs. It has been found that when the method described supra is used in practice it is sufiicient, when packing milk, to heat the inside of the tube to a temperture of about 300 C. to destroy heatresistant germs. However, the required temperature depends upon the duration of the heating time. It is known that the required temperature is greater if the heating time is shorter, and conversely. Of course, it is desired to use high temperatures in order to reduce the heating time and to correspondingly increase the speed of packing and filling if formation and filling of the receptacles is continuous.

Heating is limited by the properties of the packing material used and if the limits are exceeded, the packing material may be damaged. This applies more particularly to paperlike packing material which has a thin layer of plastic, preferably polyethylene, on the side which engages with the packed goods. As a rule, the thickness of such a layer is only a few hundredths of a millimeter. The layer serves to provide hermetic sealing of the paperlike packing mate-rial and sealing against penetration of germs and, where the receptacles are filled with liquids, against moisture soaking through to the outside of the receptacle. Paper and plastics are poor heat conductors. Therefore, if a short heating time and correspondingly high heating temperature are used, the temperature of the surface of the heated side of the material may rise very rapidly because of non-dissipation of the heat supplied, the temperature possibly rising to beyond the temperature required for sterilization, particularly if the heating device is a radiant heater.

This abrupt temperature rise may damage the heated side of the material. As a rule, polyethylene is fusible at temperatures above 100 C., while paper becomes more brittle if heated abruptly. Consequently, and also because of the stresses produced over the thickness of the material, minute cracks may open up in the plastic layer or on the paper surface and destroy hermetic sealing, involving the risk of reinfection by external germs.

Plastic layers oxidize in the presence of oxygen and ice particularly at elevated temperatures. Such oxidation impairs the properties of the plastic; it becomes more brittle and its weldability decreases so that the tightness of the welds made when closing the receptacles may be unsatisfactory.

It is an object of the invention to provide a method for sterile packing of sterile goods whereby the aforedescribed disadvantages are considerably reduced. In the method according to the invention at least that side of the material which must be heated for sterilization is moistened at the latest at the time when said side passes through the heating zone. The effect of this step is that, when the side of the material is heated, the temperature rise in the surface part of the material is initially reduced by the heating and evaporation of the moisture on or in the mate-rial, so that harmful stresses are considerably reduced and the risk of cracking the plastic is reduced. A fairly dense vapor cushion is produced which keeps atmospheric oxygen away from the plastic and thus re duces oxidation thereof. Further, the sterilizing eifect of the heating is increased, for germs such as bacteria and spores are less resistant in moist heat than in dry heat.

Preferably a wetting agent it is added to the moistening liquid to ensure a very uniform liquid film on the side of the packing material which must be protected. It is advisable to remove surplus liquid which does not adhere to the packing material, before the heating zone is entered because, otherwise, if the material passes ver tically through the heating zone, there is a chance that drops of moistening liquid run oif or drop down and come in contact again with the material below the heat ing zone, which is either detrimental to the goods to be packed or may cause reinfection because of germs present in the moistening liquid.

It may be advisable to moisten also that side of the packing material which will subsequently form the outside of the finished packages, more particularly the moisture-absorbent paper side of paper webs having one side coated with a synethetic substance. A chemically active sterilizing agent may be added to the moistening liquid for improving the sterilization eifect. This may make it possible to reduce the maximum heating temperature.

The novel features which are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, and additional objects and advantages thereof will best be understood from the following description of embodiments thereof when read in connection with the accompanying drawing wherein:

FIG. 1 is a vertical sectional view of a filling and packing machine in which a tube is formed from a continuous paper strip, partly filled and formed into closed filled receptacles by compression transversely to the longitudinal extension of the tube, the web passing through a moistening device before the tube is formed and heated.

FIG. 2 is a sectional view through a moistening device used in the machine shown in FIG. 1.

FIG. 3 illustrates a portion of a tube having a part broken off to show a heating device disposed in the tube, and a modified moistening device above the heating device.

The filling and packing machine illustrated, by Way of *AlkyI-aryl-sulfonate.

example, in the drawing comprises a casing 1 supporting a column 2. A web of paper coated on one side with a plastic, such as polyethylene, is drawn continuously off a reel, not shown, and supplied to the packing machine and is guided in a ring 3 so as to form a tube 5', the coated side of the web forming the inside wall of the tube. The side edges of the web 5 overlap one another. A heating pad 7 secured to a support 6 bears against the overlapped parts of the web 5 for connecting the parts by welding. A roller is provided inside of the formed tube adjacent to the overlapped parts and opposite the heating pad 7 for efiecting contact between the heating pad and the web. The pad 7 is electrically heated,

I Electrically heated pressing jaws 1d and 11 secured to

endless chains

12 and 13, respectively, and traveling therewith when the apparatus is in operation are provided inside the casing 1. The chain 12 runs over

guide wheels

14, 15, while the chain 13 runs over

guide wheels

16, 17, the

wheels

14 and 17 or the Wheels 1'5 and 16 being adapted to be rotated, by drive means which are not shown, to move the chains in the direction indicated by

arrows

18 and 19. Other pair of pressing jaws, not shown, are operative perpendicularly to the plane of the drawing so that the tube 5, which continuously moves in downward direction, is alternately compressed in two directions perpendicularly to one another. The move ment of whichever pressing jaws engage the tube 5 imparts a downward drive on the tube while closed receptacles 24) are formed. The goods to be packed, for instance sterilized milk, are supplied to the apparatus through filling pipe 21 which is borne by a sleeve 2 supporting at its bottom end the roller 9. The sleeve 24 is secured to an arm 4 extending from the column 2. The supply of milk is so controlled by means, not shown, that a constant liquid level 22 is maintained within the tube 5'.

' A radiant heating device 25, for example, of the type which will be described hereinafter with reference to FIG. 3, is disposed in the formed tube 5' above the introduced goods and surrounds the filling pipe 21.

Before entering the packing and filing machine the web 5 passes through a moistening device denoted in its entirety by the reference numeral 26. The device 26 is shown in section in FIG. 2 and comprises a tank 27 for moistening liquid and two

deflecting rollers

28, 29. The roller 28 dips below the level 3i? of the moistening liquid, for. instance water, to which an appropriate wetting agent can be added. Any surplus liquid which is carried along by the moving web 5 and which would drop down if the web moves vertically, returns on the upwardly incline'd part of the Web 5 between the two rollers.

When the aforedescribed apparatus is in operation, the continuously supplied web is moistened on both sides, then formed into a tube and heated by the heating device 25 on the inside of the tube whereby the liquid which adheres as a film to the inside of the tube is evaporated and the temperature rise of the tube inner wall is reduced. The vapor forms a buffer rising along the inside of the tube and being partly superheated. After passing through the heating zone the inside of the tube is completely dry until it contacts the milk filled into the tube.

FIG. 3 illustrates an embodiment wherein moist-ening is performed inside the tube formed in a filling and packing machine of the kind shown in FIG. 1. An annular duct 31 is placed in the interior of the tube 5 around the filling pipe 21 and is secured thereto in a suitable manner. Moistening liquid is suppliedthrough a connecting pipe 32 to the interior of the duct 31, the pipe 32 extending out of the top of the tube 5'. Nozzlelike apertures 33 are provided at the periphery of the I duct 31 through which pressurized moistening liquid is sprayed in very fine jets onto the inner wall of the tube 5'. Larger drops are intercepted by an interceptor ring 34 whose o ter rim touches the inside of the tube and which is made of a heat-resistant resilient substance. Below the moistcning device is a heating device 35 which comprises an annular chamber 36 containing heating coils 37. The heating device 35 is covered at the top by a heat-insulating layer 38 made of mica or the like.

An appropriate chemical sterilizing agent may be ad mixed to the moistening liquid. A solution of hydrogen eroxide has been found suitable.

The invention is not limited to the embodiments illustrated and can be used in machines wherein packing receptacles are formed in a different Way from a packing material which must be sterilized at least on the side subsequently forming the inside of the finished receptacles. Heating may be eiiected by means of a gaseous or vaporlike heat carrier. Moistening may be performed within the heating zone instead of upstream of that zone.

We claim:

1. In a method of sterile packing of sterile goods wherein a vertical tube is continuously formed from longitudinally moving strip like, flexible packing material, the tube is closed by compression transverse to the longitudinal axis of the tube, and the goods are filled into the tube, whereupon the tube is closed again by compression transverse to the longitudinal axis of the tube, the steps of:

heating the interior of the formed tube at a location above the goods for sterilizing the interior of the tube, moistening, before the packing material reaches said heating location, at least the side of the packing material whi h forms the inside of the tube,

retaining the moisture on the packing material until the packing material reaches said heating location, and

evaporating the moisture by part of the heat which heats the interior of the formed tube to reduce the initial temperature rise in the heated packing material and to produce a vapor cushion adjacent said heating location.

2. In a method of sterile packing of sterile goocs wherein a vertical tube is continuously formed from longitudinally moving striplike, flexible packing material, the tube is closed by compression transverse to the longitudinal axis of the tube, and the goods are filled into the tube, whereupon the tube is closed again by compression transverse to the longitudinal axis of the tube, the steps of:

heating the interior of the formed tube at a location above the goods for sterilizing the interior of the tube,

applying a moistening liquid, before the packing material reaches said heating location, at least to the side of the packing material which forms the inside of the tube,

retaining the moistening liquid on the packing material until the packing material reaches said heating location, and

evaporating the moistening liquid by part of the heat which heats the interior of the formed tube to reduce the initial temperature rise in the heated packing material and to produce a vapor cushion adjacent said heating location.

3. In a method as defined in claim 2 and wherein said moistening liquid contains a wetting agent.

4. In a method as defined in claim 2, the step of removing surplus moistening liquid prior to sterilization of the inside of the tube by heating.

5. In a method as defined in claim 2 and wherein said moistening liquid contains a sterilizing agent.

6. In the method defined in claim 2 wherein said moistening liquid is water.

7. in the method defined in claim 2 wherein said moistening liquid is a solution of hydrogen peroxide.

8. In a method of sterile packing of sterile goods where- D in a vertical tube is continuously formed from longitudinally moving striplilie, flexible packing material, the tube is closed by compression transverse to the longitudinal axis of the tube, and the goods are filled into the tube, whereupon the tube is closed again by compression transverse to the longitudinal axis of the tube, the steps of: moistening the inside of the formed tube at a location spaced from and above the goods in the tube,

heating the interior of the formed tube at a location above the goods and below the location Where the 10 inside of the tube is moistened, and

8 evaporating the moisture by part of the heat Which heats the interior of the formed tube to reduce the initial temperature rise in the heated packing material and to produce a vapor cushion adjacent said heating location.

References Cited in the file of this patent UNITED STATES PATENTS 2,918,770 Stocker Dec. 29, 1959 2,928,219 Gubler Mar. 15,1960 3 ,663,211 Graves Nov. 13, 1962

Claims

1. IN A METHOD OF STERILE PACKING OF STERILE GOODS WHEREIN A VERTICAL TUBE IS CONTINUOUSLY FORMED FROM LONGITUDINALLY MOVING STRIPE LIKE, FLEXIBLE PACKING MATERIAL, THE TUBE IS CLOSED BY COMPRESSION TRANSVERSE TO THE LONGITUDINAL AXIS OF THE TUBE, AND THE GOODS ARE FILLED INTO THE TUBE, WHEREUPON THE TUBE IS CLOSED AGAIN BY COMPRESSION TRANSVERSE TO THE LONGITUDINAL AXIS OF THE TUBE, THE STEPS OF: HEATING THE INTERIOR OF THE FORMED TUBE AT A LOCATION ABOVE THE GOODS FOR STERILIZING THE INTERIOR OF THE TUBE, MOISTENING, BEFORE THE PACKING MATERIAL REACHES SAID HEATING LOCATION, AT LEAST THE SIDE OF THE PACKING MATERIAL WHICH FORMS THE INSIDE OF THE TUBE, RETAINING THE MOISTURE ON THE PACKING MATERIAL UNTIL THE PACKING MATERIAL REACHES SAID HEATING LOCATION, AND EVAPORATING THE MOISTURE BY PART OF THE HEAT WHICH HEATS THE INTERIOR OF THE FORMED TUBE TO REDUCE THE INITIAL TEMPERATURE RISE IN THE HEATED PACKING MATERIAL AND TO PRODUCE A VAPOR CUSHION ADJACENT SAID HEATING LOCATION.